This invention relates in general to vehicle door lock mechanisms and in particular to a clutch providing lost motion between a motor operated mechanism and a manually operated mechanism for operating a vehicle door lock.
Vehicles such as passenger cars are commonly equipped with individual latch assemblies that secure respective passenger and driver doors closed. Each latch assembly is typically provided with a manual latch actuating mechanism for unlatching the latch assembly from outside and inside the vehicle, i.e., outer door operating thumb buttons or handles and inner door operating handles. Each latch assembly is also typically provided with an individual vehicle door lock. Vehicle door locks are well-known devices for selectively preventing a door from being unlatched by operation of the latch actuating mechanism. Vehicle door locks typically prevent unlatching of the associated latch assembly by selectively uncoupling the latch actuating mechanism from the latch assembly. Less commonly, vehicle door locks may be arranged to prevent unlatching of the associated latch assembly by selectively blocking movement of a component of the latch mechanism to prevent unlatching of the latch assembly, or by some combination of selectively uncoupling and blocking components of the latch mechanism. Vehicle door locks are typically provided with a key cylinder for manually operating the vehicle door lock mechanism from the exterior of the vehicle. Vehicle door locks are also normally provided with a manual locking mechanism for operating the vehicle door lock mechanism from the interior of the vehicle, i.e., a respective sill button. Furthermore, vehicle door locks are commonly provided with a remote lock actuating mechanism such as an electric actuator for remotely locking and unlocking the vehicle door lock.
In order to minimize the overall size of electric actuators, designers typically use relatively small electric motors to power the electric actuators. To provide the necessary torque for operating the vehicle door lock mechanism, the output from one of these electric motors is typically transmitted through a series of meshing gears formed into a gear train. This gear train amplifies the torque produced by the electric motor and applies this amplified torque to other moving parts of the vehicle door lock. The manually operated locking mechanisms are typically are connected to the vehicle door lock in parallel with the output of the gear train of the electric actuator. A relatively large amount of force is required to back-drive the gear train of the electric actuator during manual operation of the vehicle door lock. Therefore, it has been found desirable to provide a clutch in the electric actuator that uncouples the gear train and electric motor from the rest of the lock mechanism when manually operating the vehicle door lock. With the electric motor and gear train uncoupled from the rest of the lock mechanism, the force required to be exerted by a user to manually operate the lock mechanism is dramatically reduced.
As is commonly known, the vehicle door may be locked when the vehicle is unattended to prevent unauthorized entry into the vehicle. On vehicles with an interior manual locking mechanism, a thief may break a window of the vehicle and reach inside to manually unlock the latch assembly. To prevent this, it is known to provide a latch assembly with a "double lock" antitheft feature by which the interior manual locking mechanism may be selectively disabled.